Jari Honkanen

Design of digitally controlled isolating 1-phase AC/DC converter by using centralized processing unit

This paper presents a fully digital control design for 1-phase 3 kW AC/DC converter. The centralized control system is designed and implemented on microcontroller-FPGA combination. This paper emphasizes the control design flexibility for switching mode power supplies when the programmable controller approach is used.

Partial Current Harmonic Compensation in Dual Three-Phase PMSMs Considering the Limited Available Voltage

Multiphase electric machines are known to have problems with stator current harmonics. The harmonics can be eliminated by various current harmonic compensation methods. However, using the active harmonic compensation can increase the required output voltage of the inverter supplying the machine. Because the maximum voltage is limited, complete elimination of the current harmonics may not always be possible. For such cases, this paper introduces a strategy for a partial compensation of the current harmonics. The aim of the proposed strategy is to provide a maximum reduction in the magnitude of the harmonics when the available voltage is limited. The strategy is verified by experimental results.

Capacitor aging detection in DC-DC converter output stage

One of the most significant reliability issues in switching-mode power supplies is electrolytic capacitor degradation caused by aging. This paper proposes an output voltage transient analysis method to detect capacitor wear-out at the output stage of a step-down dc-dc converter. Changes in the converter output voltage dynamics are evaluated by analyzing the output voltage step response with respect to a decrease in the capacitance. The sensitivity of the method is assessed with respect to parameter variations using an equivalent main circuit model. The feasibility of the presented method is verified by experimental tests using a converter prototype. The results show that the presented method is practical and adequate for detecting capacitor degradation in various operating conditions.

Single phase PFC control with Lyapunov method

In this paper a current control method based on Lyapunov function for single phase active power factor correction (PFC) is presented. Lyapunov functions can be used for defining control law for either linear or nonlinear systems. The control is designed with cascade structure, where a voltage controller feeds the current amplitude reference to the current controller. The operation and performance are demonstrated with measurements from 3 kW power supply which uses power factor correction. The designed controller is shown to track the mains voltage with close to unity power factor.

Modulation and control methods to reduce zero sequence current in open-end winding motors

In this paper three modulation and control methods that aim to limit zero sequence current in a dual inverter fed open-end winding electrical motor are compared. When a single DC source is used in such an application, zero sequence current can circulate through the motor windings. The zero sequence current is generated by instantaneous common-mode voltage pulses from the two inverters feeding the motor. This circulating current will not only generate harmonic content in the load current, but also the current amplitude will rise, leading to unnecessary losses in the inverters and the motor. Generally a zero common-mode voltage modulation method intended for three-level inverters is applied. However, asymmetry in the switching instants is caused by dead times. Several approaches including dead time compensation, closed loop and feed forward control methods are studied to suppress the unwanted circulating current.

Luenberger state observer based condition monitoring method in digitally controlled switching mode power supply

The use of digital control in switching mode power supplies has increased as the performance of programmable controller circuits have advanced. The use of digital control provides possibility to run monitoring, prognostics and maintenance functions alongside the system core control functions. This paper suggests a model based online condition monitoring method for DC-DC power supply, based on Luenberger state observer. It is shown that abnormal operating conditions, such as increased losses in main circuit, can be detected by monitoring the state observer adaptation value variations.